The present invention relates to optical systems and in particular to optical data processing systems that incorporate magnetizable film diffraction gratings for the control of a laser light beam to determine the correlation between known and unknown signals.
In the prior art it is known that light will be diffracted by a diffraction grating. See the text "Fundamentals of Optics," Second Edition, Jenkins and White, McGraw-Hill Book Company, 1955. More recent studies with thin-magnetizable-films having a stripe domain magnetization configuration have utilized Bitter patterns formed by colloids of magnetizable powder collected along the domain walls while variable stripe domain spacing has been achieved by strong DC fields orthogonal to the plane of the field--see the text "Ferromagnetism and Ferromagnetic Domains," Craik and Tebble, Holland Publishing Company, Amsterdam, John Wiley and Sons, Inc., Volume 4, 1965. These prior art light deflectors were limited to substantially two states, minimum and maximum, of diffracted light conditions as optical display systems. See the publication "Stripe Domains in Thin Magnetic Films and Their Application to Magneto-Optical Displays," Spain and Fuller, Journal of Applied Physics, Volume 37, No. 3, Mar. 1, 1966, pages 953 to 959.
In the E. J. Torok, et al, U.S. Pat. No. 3,752,563 there is disclosed a magneto-optic light deflection system that utilizes stripe domains in a magnetizable film as a diffraction grating. The angle of deflection of the light from the plane of the film is varied in two dimensions by varying the separation and orientation of the stripe domains. The wall separation is varied by varying the intensity of a DC field in the plane of the film parallel to the stripe domains, or by varying the intensity of the DC field normal to the plane of the film. The orientation of the stripe domains is varied by varying the direction of the DC field in the plane of the film. Hysteresis in the magnetizable film is overcome by an AC tickle field applied perpendicular to the stripe domains.
In the E. J. Torok U.S. Pat. No. 3,861,784 there is disclosed an apparatus that provides the processing of an optical image using the concept of the diffraction grating of the E. J. Torok, et al, U.S. Pat. No. 3,752,563. In this E. J. Torok patent there is disclosed an apparatus that is capable of varying the separation of adjacent domain walls and the rotatable orientation of the parallel stripe-domains. The resulting system is utilized to control, by the Kerr or Faraday effect, the focus of a light beam that is directed upon the plane of the magnetizable film. The apparatus includes a plurality of stripline arrays configured to permit the individual and selective control of a separation and the orientation of domain walls in each individual portion of the magnetizable film. This selective control of the domain wall separation and orientation in each individual portion of the magnetizable film permits an arbitrary configuration of domain walls of substantially continuously varying spacing and direction. Domain wall arrangements of different fixed configurations perform various imaging processing functions include a grating: to remove linear distortion: to remove U shaped distortions; to perform the function of a lens; to perform simultaneously the function of a lens and a translation of the image; to rotate the image; and, to simultaneously rotate and translate the image. The present invention is considered to be an improved apparatus for a method of rotating an optical image, using a magnetizable film formed diffraction grating.